With utilizing a magnetic head using a magnetoresistive element, a magnetic recording apparatus has improved its recording density at remarkable speed.
However, as for the magnetic head using the magnetoresistive element there is still a problem that should cope with shot noise and white noise because those noises cause reducing an S/N (signal noise) ratio.
In order to solve this problem, applying a spin torque oscillator as a magnetic sensor has been proposed to realize a high S/N ratio.